If a country has a lot of foreign exchange reserves, it can buy a lot of gold, but the United States will not be stupid enough to let you buy a lot of gold. Even if you can, once you have a lot of money to buy any goods, it will definitely cause the price of goods to skyrocket, and it is not impossible to increase several times. If the price of gold soars, the risk of buying is much greater than that of buying US Treasury bonds.